Power outages and voltage disturbances can cause extensive damage to industrial processes and data loss in information systems. Momentary disturbances (e.g., disturbances with a duration of less than 5 seconds) account for the large majority of interruptions or voltage sags experienced on utility feeders.
Solutions for providing sag or interruption mitigation on utility feeders have been proposed. For example, it has been proposed to protect an entire utility feeder with a system in which an inverter and power electronics continuously supply power to the critical load to be protected. These solutions entail high costs, and several of them only provide sag mitigation as opposed to sag and interruption mitigation. They are therefore unable to prevent critical load outages in which the utility feeder opens, or in which sags occur coincident with a large phase angle offset as is normally the case for voltage disturbances resulting from transmission line faults.
Accordingly, a goal of the present invention is to provide a cost-effective solution for reliably mitigating voltage disturbances and interruptions.